1.Field of the Invention
This invention relates to the field of network delivery of audio and video information. In particular, the invention relates to a system for delivering audio and video information to multiple users.
2. Background Information
The Internet enables many different ways of communicating. Originally, the Internet was used for the exchange of files and electronic mail. As the capabilities of the Internet expand, other types of communications are enabled.
Audio and video transmissions are an important area of the communications that the Internet enables. For example, many technologies support the transmission of digital video and/or audio signals over the Internet. An example of such a technology is Quicktime(trademark), available from Apple Computer, Inc., of Cupertino Calif. Quicktime movies are files that can be transmitted across the Internet. Quicktime provides both audio and video displays. Many other file formats allow audio and video to be displayed on people""s computers.
This paragraph describes an example use of a the Quicktime technology. A user will have a browser application that resides on his/her computer. The computer, acting as a client under the direction of the browser application, will connect to various World Wide Web (web) servers. Each web server will typically serve hypertext markup language (HTML) files to the clients. The files may include text, graphics references, and references to specialized files. Some of these specialized files can include audio and video information in Quicktime form. The clients can then play these audio and video files once they are downloaded using a Quicktime plug-in, a helper application, or Quicktime capabilities built into the browser application. A plug-in and a helper application are described in greater detail below.
Streaming audio and video, as a subset of all the types of audio and video that can be transmitted over the Internet, allow people to broadcast long and/or live video and audio transmissions across the Internet. Streaming video and audio is video and audio digital data that is transmitted on a continuous basis. A client can access the data stream and regenerate the video images and audio signal as they are being transmitted. Streaming technology is particularly helpful where the events are live, or where the files would be so large as to be a burden on the end users. Examples of where streaming technology is particularly useful are for the display of conferences, sporting events, radio broadcasts, television broadcasts, and the like.
RealNetworks, Inc. of Seattle, Wash., provides a system for transmitting streaming audio and video signals to users over the Internet. RealNetworks supplies a server that allows multiple users to simultaneously receive streaming audio and video.
The real audio system requires that not only the client have additional software, but that the content provider have a separate server from their normal web server. For a client to receive a real audio broadcast, the client typically connects through their browser to a Web page with a reference to a real audio server. The client then accesses its separate real audio player program. The real audio player program then connects to the referenced real audio server. A significant drawback to such an arrangement is that the user must download the real audio player program. This program must then be installed on the user""s computer. This may cause a number of problems for the user. For example, if the user is behind a firewall, or some security program, the client may not be able to receive the broadcast from the server. Additionally, the installation of any program may have conflicts with other programs. The program has the disadvantage of being platform specific. This means that a different program must be developed and downloaded for each type of computer that is to be used to access RealNetworks broadcasts. Additionally, the broadcasters of the streaming audio and video need to use the RealNetworks server, which is separate from the broadcasters"" World Wide Web server (also referred to as the web server). This increases the broadcasters"" security problems because now the broadcasters must be concerned with two separate servers.
Another example of a video and audio system that uses Internet like communications is the MBone. The MBone is a specialized communication network that allows for the distribution of streaming video and audio signals to multiple users. A specialized network is set up specifically to transmit MBone communications. A significant drawback of this system is that users must be connected to the specialized network. Additionally, users will be required to have specialized software on their computers to listen to and watch MBone transmissions.
A streaming video system, not requiring a user to download a separate program, was developed for a single user by John Graham of California. This single user broadcast technology allowed a web server to serve a single streaming video signal to a single client. Although the user did not need to download a plug-in to see the video, only one user was allowed to access the video stream at a time. In this system, video information was captured from a video camera and digitized. The digital video information was then encapsulated in a MIME encoded multipart data stream. The client received this data stream and reconstructed frames of the digital video.
Therefore, what is desired is a platform independent video and audio streaming system that does not require the user to download additional programs beyond the functionalities found in a browser.
A system and method of providing streaming audio and video data to multiple users is described. In one embodiment, the system comprises a first client, a second client and a server. The first and second clients are executing browsers. The server can communicate with the two clients. The server concurrently provides streaming audio and video data to both of the clients. Importantly, the server does not require the two browsers to use a plug-in or a helper application to receive and use the streaming audio and video data.
In some embodiments of the invention, a browser causes a client to request an HTML file from a web server. The client receives the HTML file. The HTML file includes an HTML tag that directs the browser to load one or more applets from the server. The browser executes the applets causing the browser to request streaming audio and video from the web server. That request may or may not include parameters giving information about the type of request being made. The web server associates a server process with the request, given the parameters in the request. The web server notifies real-time audio and video process that streaming audio and video information is needed. In response to the notification, the real-time audio and video process stores encoded audio and video data in a shared memory location. The server process accesses the shared memory and inserts the audio and video data into one or more data streams. The client receives the data streams and reconstructs the audio and video signals using only the capabilities of the browser. In some embodiments, a separate stream and server process is used for each of the audio and video data. These embodiments allow multiple clients to simultaneously receive the same audio and video data.
Other embodiments of the invention include a web server that can serve streaming audio and video information as well as perform more usual web server functions (such as, serving web pages, performing file transfers, supporting secure communications). These embodiments have the advantage of allowing the broadcasters and the users to set up their security configurations for one web server, rather than two servers (a web server and a streaming audio and video server).